1. Field of the Invention
The present invention relates to an organic light emitting display device and, more particularly, to a transparent organic light emitting display device.
2. Description of the Related Art
Applications of organic light emitting display devices range from personal portable devices, such as MP3 players and mobile phones, to television sets due to having superior characteristics, such as wide viewing angles, high contrast ratios, short response times, and low amounts of power consumption.
An organic light emitting display device has self-light emitting characteristics, and the weight and thickness of the organic light emitting display device can be reduced since the organic light emitting display device, unlike the liquid crystal display device, does not require an additional light source.
Also, an organic light emitting display device can be formed so as to be a transparent display device by having transparent thin film transistors and transparent organic light emitting devices.
In a transparent display device, when the device is in an off-state, an object or an image positioned on a side of the device opposite to the user is transmitted to the user not only through organic light emitting diodes but also through patterns of thin film transistors and various wires and through spaces between the patterns of thin film transistors and various wires. Even in the transparent display device, transmittances of the above-described organic light emitting diodes, the thin film transistors, and the wires are not so high, and spaces between the organic light emitting diodes, the thin film transistor, and the wires are very small, and thus the transmittance of the transparent display device is not high.
Also, a distorted image may be transmitted to the user due to the above-described patterns, i.e., the patterns of the organic light emitting diodes, the thin film transistors, and the wires. The reason for this is because gaps between the patterns are only a few nanometers, that is, at a level almost close to the wavelengths of visible light, and thus the gaps scatter light therethrough.
Furthermore, when an opposite electrode to be commonly deposited on the entire screen in order to improve transmittance of external light, voltage drop (i.e., IR drop) may occur in the opposite electrode, and in particular, as the size of an organic light emitting display device increases, voltage drop may occur remarkably.